Infection by hepatitis C virus (“HCV”) is a compelling human medical problem. HCV is recognized as the causative agent for most cases of non-A, non-B hepatitis, with an estimated human sero-prevalence of 3% globally (A. Alberti et al., “Natural History of Hepatitis C,” J. Hepatology, 31 (Suppl. 1), pp. 17-24 (1999)). Nearly four million individuals may be infected in the United States alone. (M. J. Alter et al., “The Epidemiology of Viral Hepatitis in the United States,” Gastroenterol. Clin. North Am., 23, pp. 437-455 (1994); M. J. Alter “Hepatitis C Virus Infection in the United States,” J. Hepatology, 31 (Suppl. 1), pp. 88-91 (1999)).
Upon first exposure to HCV, only about 20% of infected individuals develop acute clinical hepatitis while others appear to resolve the infection spontaneously. In almost 70% of instances, however, the virus establishes a chronic infection that may persist for decades. (S. Iwarson, “The Natural Course of Chronic Hepatitis,” FEMS Microbiology Reviews, 14, pp. 201-204 (1994); D. Lavanchy, “Global Surveillance and Control of Hepatitis C,” J. Viral Hepatitis, 6, pp. 35-47 (1999)). Prolonged chronic infection can result in recurrent and progressively worsening liver inflammation, which often leads to more severe disease states such as cirrhosis and hepatocellular carcinoma. (M. C. Kew, “Hepatitis C and Hepatocellular Carcinoma”, FEMS Microbiology Reviews, 14, pp. 211-220 (1994); I. Saito et. al., “Hepatitis C Virus Infection is Associated with the Development of Hepatocellular Carcinoma,” Proc. Natl. Acad. Sci. USA, 87, pp. 6547-6549 (1990)). Unfortunately, there are no broadly effective treatments for the debilitating progression of chronic HCV.
Compounds described as protease inhibitors, and in particular serine protease inhibitors, useful in the treatment of HCV infections are disclosed in WO 02/18369. Also disclosed therein in this publication are processes and intermediates for the preparation of these compounds, which lead to racemization of certain steric carbon centers. See, e.g., pages 223-22. There remains however, a need for economical processes for the preparation of these compounds.